The invention concerns generally the use of certain protocols and services for conveying certain types of information between the different nodes of a telecommunication network. Especially the invention concerns the use of such protocols and services to facilitate the use of the Wireless Application Protocol between a terminal of a cellular radio network and a node computer of a fixed packet-switched network.
The Wireless Application Protocol (WAP) is a result of the efforts of an internationally acknowledged instance known as the WAP Forum to promote industry-wide specifications for technology used for developing applications and services that operate over wireless networks, such as GSM (Global System for Mobile telecommunications). WAP specifies an application framework and a set of network protocols for wireless devices such as mobile telephones and personal digital assistants (PDAs). The lowest layer of the WAP protocol stack is the WDP (Wireless Datagram Protocol) layer. The WDP layer should operate above a bearer service supported by a wireless network and capable of conveying data transmissions. In the existing GSM networks WAP is usually implemented using the Short Message Service or SMS as the bearer below the WDP layer, but in such arrangements the limitations inherent to the SMS are seriously restricting the applicability of the WAP.
Novel radio telecommunication systems with inherent packet-switched communication capabilities and/or connections to fixed packet-switched networks are currently being specified. As an example we will consider the system of FIG. 1, where a terminal 101 is a UMTS (Universal Mobile Telecommunications System) terminal operating in a UMTS network 103 and terminal 102 is an enhanced GSM terminal operating in an enhanced GSM network 104. From both networks there is a connection to a GPRS (General Packet Radio Service) network 105. The UMTS network 103 comprises a UTRAN or UMTS Terrestrial Radio Access Network 106 as well as a CN or Core Network 107. In the enhanced GSM network 104 a BSS or Base Station Subsystem 108 and an MSC or a Mobile Switching Centre 109 are shown. The detailed structure of the network elements is unessential to the present invention, but it is known that for example a UTRAN consists of a number of Radio Network Subsystems, each of which in turn comprises a Radio Network Controller and a number of Node Bs roughly corresponding to base stations. A BSS in turn comprises a Base Station Controller and a number of Base Transceiver Stations operating under it. Various mixed-mode cellular telephone systems are possible; for example the BSS 108 might operate under the same CN as the UTRAN 106. The terminals could also be exactly similar terminals operating close to each other in a single cell.
In FIG. 1 there is a connection both from the UTRAN 106 and from the BSS 108 to a corresponding SGSN or Serving GPRS Support Node 110 and 111. Both of these are in turn coupled, through the GPRS trunk lines, to a GGSN or Gateway GPRS Support Node 112 from which there is a further connection to WAP gateway 113. The WAP gateway may also be known as a WAP proxy, and it could also be realised as a part of the GGSN 112; in FIG. 1 it is independent of the GGSN and not even a part of the GPRS network but connected to it through the Internet 114. If the above-mentioned SMS arrangement were used as the bearing service between a terminal 101 or 102 and the WAP gateway 113, there should also be a SMSC or Short Message Switching Centre coupled to the CN 107 and the MSC 109, and the direct connections from the UTRAN 106 and the BSS 108 to the GPRS network could not be utilized. However, it has been proposed that the routing shown in FIG. 1 should in the future be used for all data traffic between the terminals and the fixed packet-switched networks.
At the time of filing this patent application there does not exist an unambiguously defined way of using the lower-level protocol layers and PDP Contexts (Packet Data Protocol) in the terminals and fixed network devices to convey the messages related to the use of the WAP. It is clear that somewhere at a relatively high level in the protocol stacks of both the terminals 101 and 102 and the WAP-GW 113 there must be a WDP entity that uses the services offered by the lower level protocols to convey the WAP-related messages. Additionally those messages must be mapped into PDP Contexts of certain type; the mapping will be closely related to the choice of lower protocol layers under the WDP entity. We anticipate that network operators will require the WAP usage to be distinguishable from other forms of packet-switched data transmission in order to arrange for a suitable charging scheme for the WAP-related services.
A proposed prior art approach for conveying WAP-related messages is to build the WAP-related messaging on top of the known IP or Internet Protocol PDP Type. This would require the GGSNs to reserve and allocate dynamic IP addresses to mobile users. The use of dynamic addresses is not efficiently combined to WAP services, and in any case using the IP PDP Type for WAP messaging would consume the scarce IP addresses and involve the whole complexity of allocating and maintaining IP addresses and dynamically configuring hosts. A terminal roaming in another network should in practice always use the WAP-GW of its home network, because there is no possibility of dynamically telling the IP addresses of other WAP-GWs to the terminal.
It is an object of the present invention to provide a feasible method and a corresponding arrangement for conveying WAP-related messages between terminals and WAP-GWs. It is an additional object of the invention that the proposed method does not require exhaustive respecification in the framework of existing standards and proposals. A further object of the invention is to minimize the required protocol overhead in the WAP-related traffic between the terminals and the WAP-GWs. An even further object of the invention is to provide means for distinguishing the WAP-related traffic from other types of packet-switched information transfer.
The objects of the invention are met by using the OSP or Octet Stream Protocol, known as such, to carry a data stream comprising the required WAP-related information.
The method according to the invention is characterized in that it comprises the steps of
defining a Wireless Datagram Protocol layer as a certain layer above the octet stream protocol layer in the protocol stacks of a terminal arrangement and a network device arrangement and
exchanging information related to the use of the Wireless Application Protocol between the Wireless Datagram Protocol layer in the terminal arrangement and the Wireless Datagram Protocol layer in the network device arrangement through the use of the octet stream protocol layer as well as other lower layers in the first and second protocol stacks.
The invention also applies to a terminal arrangement which is characterized in that its control entity is arranged to
implement a Wireless Datagram Protocol layer in a protocol stack and
exchange information related to the use of the Wireless Application Protocol between said Wireless Datagram Protocol layer in the protocol stack and a network device arrangement through the use of the octet stream protocol layer as well as other lower layers in the protocol stack.
Additionally the invention applies to a network device arrangement which is characterized in that its control entity is arranged to
implement a Wireless Datagram Protocol layer in a protocol stack and
exchange information related to the use of the Wireless Application Protocol between said Wireless Datagram Protocol layer in the protocol stack and a terminal arrangement through the use of the octet stream protocol layer as well as other lower layers in the protocol stack.
The Octet Stream Protocol or OSP is a previously defined way in GPRS for carrying relatively unstructured information in the form of octet streams between a mobile terminal and a GGSN. An octet is a group of eight consecutive bits. There exists a ready specified PDP Type for OSP, and in the known protocol stacks related to GPRS the OSP entity is directly on top of the SNDCP (Subnetwork Dependent Convergence Protocol) layer in the terminal and on top of the GTP (GPRS Tunneling Protocol) in the GGSN. Additionally there exists a known way for a GGSN to operate as a mediator between an OSP-carried connection in the direction of a mobile terminal and further network devices like a WAP gateway. According to the invention the WDP protocol entity will be placed on top of the OSP entity in the terminal, and on top of the OSP entity or a corresponding, mapped entity in the WAP gateway. Other protocol entities may take the role of adaptation layers therebetween if required.
A PDP Context activation procedure between a terminal and a GGSN is required to enable the transmission of WAP-related messages in the framework of OSP. The device that initiates the activation procedure transmits an Activate PDP Context Request that contains a set of parameters that are required to identify and define the desired PDP Context. In the case of terminal-initiated PDP Context activation the SGSN may need to select the appropriate GGSN on the basis of the parameters contained within the activation request and possibly using also previously stored information about the home location of the terminal. If the WAP-GW functionality is not implemented within a GGSN, a specific interface may be needed to define the transmission of information therebetween.
After the PDP Context setup has been accomplished, WAP-related messages are conveyed as an octet stream by using either the octet mode, where the OSP protocol entity applies a packet assembly/disassembly function, or the block mode where no separate packet assembling or disassembling is performed.
The invention has several advantageous features. Using OSP as the bearer for WAP makes it possible to minimize protocol overheads because OSP does not require a large amount of associated control information. The PDP Context used to convey WAP-related messages may be completely separated from all other PDP Contexts even without defining a new PDP Type, which makes it easy to define a separate charging scheme for WAP usage. No IP addresses or other addresses of an external network are required for the transmission of WAP-related messages, which decreases configuration efforts, bypasses dynamic address allocation procedures and saves the operators from assigning static external network addresses to all users wishing to use WAP. Only the terminal and the WAP-GW or GGSN must interpret the data travelling through a xe2x80x9ctransparent tunnelxe2x80x9d between a terminal and a SGSN on one hand, between a SGSN and a GGSN on the other hand and between a GGSN and a WAP-GW on still another hand if the GGSN and the WAP-GW have been implemented separately. Contents of the tunnels are transparent to GPRS/UMTS network elements (only MS/UE and WAP proxy/gateway have to interpret the data travelling through the tunnels). This allows flexible implementation and enhancement of the WDP protocol.
The utilization of an unstructured octet stream between a terminal and a WAP-GW or GGSN enables the operators to direct the WAP-carrying PDP Contexts of desired users always to a particular WAP-GW/GGSN; for example the one residing in the user""s home network. On the other hand, operators may also allow any WAP-GWs to be used, but this may restrict the service to the mobile-originated alternative only. In any case the control possibilities are much more flexible than in the IP-based prior art solutions. A terminal may even select a desired WAP-GW/GGSN by using a certain predefined parameter in an Activate PDP Context Request.